diff --git a/ui/src/actions/tasksActions.ts b/ui/src/actions/tasksActions.ts
index ea9b50e..57caf27 100644
--- a/ui/src/actions/tasksActions.ts
+++ b/ui/src/actions/tasksActions.ts
@@ -1,4 +1,5 @@
 import {
+  cancelActiveTask,
   listActiveTasks,
   ListActiveTasksResponse,
   listDeadTasks,
@@ -29,6 +30,9 @@ export const LIST_RETRY_TASKS_ERROR = "LIST_RETRY_TASKS_ERROR";
 export const LIST_DEAD_TASKS_BEGIN = "LIST_DEAD_TASKS_BEGIN";
 export const LIST_DEAD_TASKS_SUCCESS = "LIST_DEAD_TASKS_SUCCESS";
 export const LIST_DEAD_TASKS_ERROR = "LIST_DEAD_TASKS_ERROR";
+export const CANCEL_ACTIVE_TASK_BEGIN = "CANCEL_ACTIVE_TASK_BEGIN";
+export const CANCEL_ACTIVE_TASK_SUCCESS = "CANCEL_ACTIVE_TASK_SUCCESS";
+export const CANCEL_ACTIVE_TASK_ERROR = "CANCEL_ACTIVE_TASK_ERROR";
 
 interface ListActiveTasksBeginAction {
   type: typeof LIST_ACTIVE_TASKS_BEGIN;
@@ -115,6 +119,25 @@ interface ListDeadTasksErrorAction {
   error: string; // error description
 }
 
+interface CancelActiveTaskBeginAction {
+  type: typeof CANCEL_ACTIVE_TASK_BEGIN;
+  queue: string;
+  taskId: string;
+}
+
+interface CancelActiveTaskSuccessAction {
+  type: typeof CANCEL_ACTIVE_TASK_SUCCESS;
+  queue: string;
+  taskId: string;
+}
+
+interface CancelActiveTaskErrorAction {
+  type: typeof CANCEL_ACTIVE_TASK_ERROR;
+  queue: string;
+  taskId: string;
+  error: string;
+}
+
 // Union of all tasks related action types.
 export type TasksActionTypes =
   | ListActiveTasksBeginAction
@@ -131,7 +154,10 @@ export type TasksActionTypes =
   | ListRetryTasksErrorAction
   | ListDeadTasksBeginAction
   | ListDeadTasksSuccessAction
-  | ListDeadTasksErrorAction;
+  | ListDeadTasksErrorAction
+  | CancelActiveTaskBeginAction
+  | CancelActiveTaskSuccessAction
+  | CancelActiveTaskErrorAction;
 
 export function listActiveTasksAsync(
   qname: string,
@@ -247,3 +273,20 @@ export function listDeadTasksAsync(
     }
   };
 }
+
+export function cancelActiveTaskAsync(queue: string, taskId: string) {
+  return async (dispatch: Dispatch<TasksActionTypes>) => {
+    dispatch({ type: CANCEL_ACTIVE_TASK_BEGIN, queue, taskId });
+    try {
+      await cancelActiveTask(queue, taskId);
+      dispatch({ type: CANCEL_ACTIVE_TASK_SUCCESS, queue, taskId });
+    } catch {
+      dispatch({
+        type: CANCEL_ACTIVE_TASK_ERROR,
+        error: `Could not cancel task: ${taskId}`,
+        queue,
+        taskId,
+      });
+    }
+  };
+}
diff --git a/ui/src/api.ts b/ui/src/api.ts
index 19d40a1..4e31479 100644
--- a/ui/src/api.ts
+++ b/ui/src/api.ts
@@ -170,6 +170,16 @@ export async function listActiveTasks(
   return resp.data;
 }
 
+export async function cancelActiveTask(
+  qname: string,
+  taskId: string
+): Promise<void> {
+  await axios({
+    method: "post",
+    url: `${BASE_URL}/queues/${qname}/active_tasks/${taskId}/cancel`,
+  });
+}
+
 export async function listPendingTasks(
   qname: string,
   pageOpts?: PaginationOptions
diff --git a/ui/src/reducers/tasksReducer.ts b/ui/src/reducers/tasksReducer.ts
index ad5cbed..c1a112f 100644
--- a/ui/src/reducers/tasksReducer.ts
+++ b/ui/src/reducers/tasksReducer.ts
@@ -15,6 +15,9 @@ import {
   LIST_DEAD_TASKS_BEGIN,
   LIST_DEAD_TASKS_SUCCESS,
   LIST_DEAD_TASKS_ERROR,
+  CANCEL_ACTIVE_TASK_BEGIN,
+  CANCEL_ACTIVE_TASK_SUCCESS,
+  CANCEL_ACTIVE_TASK_ERROR,
 } from "../actions/tasksActions";
 import {
   ActiveTask,
@@ -24,11 +27,21 @@ import {
   ScheduledTask,
 } from "../api";
 
+interface ActiveTaskExtended extends ActiveTask {
+  // Indicates that a request has been sent for this
+  // task and awaiting for a response.
+  requestPending: boolean;
+
+  // Incidates that a cancelation signal has been
+  // published for this task.
+  canceling: boolean;
+}
+
 interface TasksState {
   activeTasks: {
     loading: boolean;
     error: string;
-    data: ActiveTask[];
+    data: ActiveTaskExtended[];
   };
   pendingTasks: {
     loading: boolean;
@@ -101,7 +114,11 @@ function tasksReducer(
         activeTasks: {
           loading: false,
           error: "",
-          data: action.payload.tasks,
+          data: action.payload.tasks.map((task) => ({
+            ...task,
+            canceling: false,
+            requestPending: false,
+          })),
         },
       };
 
@@ -235,6 +252,53 @@ function tasksReducer(
         },
       };
 
+    case CANCEL_ACTIVE_TASK_BEGIN: {
+      const newData = state.activeTasks.data.map((task) => {
+        if (task.id !== action.taskId) {
+          return task;
+        }
+        return { ...task, requestPending: true };
+      });
+      return {
+        ...state,
+        activeTasks: {
+          ...state.activeTasks,
+          data: newData,
+        },
+      };
+    }
+
+    case CANCEL_ACTIVE_TASK_SUCCESS: {
+      const newData = state.activeTasks.data.map((task) => {
+        if (task.id !== action.taskId) {
+          return task;
+        }
+        return { ...task, requestPending: false, canceling: true };
+      });
+      return {
+        ...state,
+        activeTasks: {
+          ...state.activeTasks,
+          data: newData,
+        },
+      };
+    }
+
+    case CANCEL_ACTIVE_TASK_ERROR:
+      const newData = state.activeTasks.data.map((task) => {
+        if (task.id !== action.taskId) {
+          return task;
+        }
+        return { ...task, requestPending: false };
+      });
+      return {
+        ...state,
+        activeTasks: {
+          ...state.activeTasks,
+          data: newData,
+        },
+      };
+
     default:
       return state;
   }